2x+3y=60 solve for x...
x=(60-3y)/2
p=xy^3, using x from above:
p=y^3(60-3y)/2
p=(60y^3-3y^4)/2
dp/dy=(180y^2-12y^3)/2
dp/dy=90y^2-6y^2
dp/dy=0 when:
90y^2-6y^3=0
6y^2(15-y)=0, we know y>0 so
y=15, since x=(60-3y)/2
x=7.5
(We solved it this way because otherwise you get quartic equations and cubic derivatives, yuck :P)
Add 12 to both sides of the equal sign, then simplify.
Answer:
12565.11 teeth approximately cut cross the cutting surface per seconds.
Step-by-step explanation:
Since the diameter is 10inches, the circumference of the arm saw is 10π (circumference is πd where d is diameter).
The number of teeth on the cutting blade can be gotten by multiplying the diameter by 12 since we have 12 teeth per inch on the arm saw
Number of teeth on saw = 12 x 10π = 120π.
To get the number of teeth that cross the cutting surface in 2000rpm we multiple it by the total number of teeth in just one rpm.
So we have 2000 x 120π. But since we are asked to find it in revolution per seconds then 2000r/m = 2000r/60s ≈ 33.33
Therefore, we have
33.33 x 120π ≈ 12565.11 teeth
Work shown above! Hopefully this is what you were looking for
